1. Field of the Invention
The present invention relates to an oil filter to be incorporated in a lubricating system for an internal combustion engine or the like and, more particularly, to an oil filter of a type in which not only solid contaminants but also gaseous contaminants can be removed from the oil.
2. Description of the Prior Art
In machinery for construction, transportation and the like using lubricant, such as engines and various hydraulic devices, solid contaminants and gaseous contaminants have hitherto been removed from lubricant by separate devices and/or in different portions of the machinery. A device has thus been desired which can remove both of the solid and gaseous contaminants effectively and which can be installed in a limited space of the machinery.
The inventors herein have proposed an integrated device in a pending Japanese Patent Application No. 202682/88 filed Aug. 16, 1988. The device disclosed therein comprises a first separator having a filter element for filtering lubricant which is pumped into a housing to thereby remove solid contaminants, and a second separator for removing gaseous contaminants from the filtered oil by utilizing a centrifugal force. Specifically, the second separator has a chamber adapted to generate a vertical flow of the lubricant introduced therein, whereby the lubricant having little gaseous contaminants and therefore having a larger specific gravity gathers in a peripheral area of the chamber while gas-rich lubricant having a smaller specific gravity gathers in a central area. A wall defining the chamber is provided with a plurality of pores through which the gas-removed lubricant flows out of the chamber. On the other hand, the gas-rich lubricant is discharged by a perforated pipe which extends into the chamber along its axis.
In the above proposed device, both the first and second separators are arranged within a housing which is to be attached to a mount block in a lubricating system. The mount block should in turn be provided with various passages to supply the lubricant into the housing, lead the filtered and gas-removed lubricant to various parts to be lubricated, and to discharge the gas-rich lubricant into a tank for recirculation, and attachment of the housing involves connecting these passages to respective portions of the housing. However, the above device is not so constructed that it may easily be attached to the mount, and relatively complicated work will be needed for the attachment. This is particularly important because, as is well known in the art, the filter element is subjected to replacement due to its clogging during a use of the device.
For a conventional type oil filter adapted to remove only the solid contaminants, it is an usual practice to replace the oil filter as a whole, i.e. including a housing. Although such a practice has been found desirable, application thereof to the above proposed device would be a waste of the second separator which can be used semi-permanently. Further, there are many replacement units of the conventional oil filter available in the market, but those units can not be used for the above proposed device.